Ultrasound imaging has provided useful information about the interior characteristics of an object or subject under examination. An ultrasound scanner has included a probe with a transducer array that is configured to transmit an ultrasound signal into the object or subject under examination. As the signal traverses the object or subject under examination, portions of the signal are attenuated, scattered, and/or reflected off structure and/or boundaries in the interior of the object or subject, with some of the reflections traversing back towards the transducer array. The later reflections are referred to as echoes and are detected by the transducer array.
In B-mode imaging, the echoes correspond to an axial slice through the object or subject and are processed to generate scanlines of a scanplane, or two dimensional image of the slice, which can be displayed via a monitor. B-mode scanplanes have been combined with color flow mapping (CFM) data and/or other special mode data. However, in order to maintain a reasonably high frame rate (e.g., 10-20 Hz) and full resolution (e.g., high line density), the CFM data is acquired and shown only in a smaller viewport superimposed over only a sub-portion of the B-mode image, with the B-mode image providing an anatomical frame of reference. Furthermore, when panning the viewport, the CFM data update has been delayed such that aged or non-current CFM data is displayed.
For example, FIGS. 1-3 show an approach in which the CFM data in the viewport is not refreshed until the viewport is moved to a new location. In FIG. 1, a main window 102 displays a B-mode image 104 and a viewport 106, which is located at a first location 108, displays first CFM data 110. In FIG. 2, the viewport 106 is being moved (e.g., dragged via a mouse) to a second different location 112. However, the first (now aged) CFM data 110 remains at the first location and the viewport 106 does not show any CFM data. In FIG. 3, the viewport 106 is at the second different location 112 (e.g., dropped via the mouse) and the CFM data is refreshed with new current CFM data 114 and the aged CFM data 110 is removed from the main window 102. In this example, the refresh rate of the main window 102 and the viewport 106 at the first or the second locations 108 and 112 is 10-20 Hz, but the refresh of the CFM data in the viewport 106 when moving the viewport 106 might now occur with a one or more second delay, depending on how long it takes the user to move and place the viewport 106.
FIGS. 4-7 show another approach in which refreshed CFM data lags in time behind the moving viewport 106 as a still image 202 and, likewise, the viewport 106 is not refreshed with the current CFM data 114 until it is at its new position 112. In this example, the refresh rate of the main window 102 and the viewport 106 at the first or the second locations 108 and 112 is 10-20 Hz, but the refresh of the CFM data when moving the viewport 106 might now occur with a 0.3 second or more delay until the viewport is at the new location 112. When moving the viewport 106 in these approaches, the acquisition algorithm is changed on the fly to acquire the lines within the viewport 106 for each update of the image data in the viewport 106. Typically the change of acquisition algorithm for the active scanning modes requires a large amount of recalculation of hardware settings. This is a reason for the lag in the image update within the viewport while it is moving.
Unfortunately, neither of the above approaches is well-suited for observing CFM data or other special mode data at least because during the time period in which the viewport 106 is being moved current (live, real-time) CFM data is not displayed. Rather, aged CFM data is displayed during this time period, and the CFM data in the viewport 106 is refreshed only such that it lags in time by 0.3 or more seconds behind current CFM data. In one instance, this renders these two approaches not very useful nor provides a good user experience.